/*
 * @(#)$Id: FastByteArrayInputStream.java 3619 2008-03-26 07:23:03Z yui $
 * 
 * Copyright 2006-2008 Makoto YUI
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 * 
 * Contributors: Makoto YUI - initial implementation
 */
package jacky.lanlan.song.io.stream;

import java.io.InputStream;

/**
 * ByteArrayInputStream implementation that does not synchronize methods.
 */
public final class FastByteArrayInputStream extends InputStream {

	protected final byte[] buf;

	protected final int count;

	protected int pos = 0;

	public FastByteArrayInputStream(byte[] buf) {
		this(buf, buf.length);
	}

	public FastByteArrayInputStream(byte[] buf, int count) {
		this.buf = buf;
		this.count = count;
	}

	public FastByteArrayInputStream(byte buf[], int offset, int length) {
		this.buf = buf;
		this.pos = offset;
		this.count = Math.min(offset + length, buf.length);
	}

	@Override
	public final int available() {
		return count - pos;
	}

	public final int read() {
		return (pos < count) ? (buf[pos++] & 0xff) : -1;
	}

	@Override
	public final int read(byte[] b, int off, int len) {
		if (pos >= count) { return -1; }
		if ((pos + len) > count) {
			len = (count - pos);
		}
		if (len <= 0) { return 0; }
		System.arraycopy(buf, pos, b, off, len);
		pos += len;
		return len;
	}

	@Override
	public final long skip(long n) {
		if ((pos + n) > count) {
			n = count - pos;
		}
		if (n < 0) { return 0; }
		pos += n;
		return n;
	}

	@Override
	public boolean markSupported() {
		return false;
	}

	@Override
	public void mark(int readlimit) {
		throw new UnsupportedOperationException();
	}

}